Plenum Kit

ABSTRACT

A plenum assembly for a shallow chassis in a rack-mount system. The rack mount system includes a first set of posts at a first end of the rack, a second set of posts at a second end of the rack, and guide rails that extend between the first and second sets of posts. A shallow chassis mounted on the guide rails extends from the first end of the rack to an intermediate location, between the first and second ends of the rack. The plenum assembly is also mounted on the guide rails, and extends from the second end of the rack to the intermediate location, providing an airway from the second end of the rack to the shallow chassis. The plenum assembly can include telescoping sections to extend various lengths. Alternately, the plenum assembly can have a two piece construction, which is assembled after routing cables to the shallow chassis.

RELATED APPLICATION

This application claims priority from U.S. Provisional Patent Application 61/578,737, entitled “Plenum Kit”, which was filed on Dec. 21, 2011, and is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a rack mountable plenum kit.

RELATED ART

‘Pizza box’ and chassis-based systems are typically housed in racks or rack cabinets. The depths of the systems into the rack vary. One end (front or back) of all the systems in a rack are typically aligned to a set of posts in the rack. For example, the front end of all systems mounted in the rack may be aligned with a set of front posts in the rack. Airflow in the rack can be front to back or back to front. The intake side is designated the “cool aisle” while the exhaust side in designated the “warm aisle”. There can be interfaces and connections on either side of the system which need easy access. An issue occurs when systems of different depths are housed in the same rack. There is the possibility of warm exhaust air being re-circulated into the intakes of a less deep chassis. This issue is illustrated by FIGS. 1 and 2.

FIG. 1 is a top view of a typical pizza box chassis 100, which includes power supplies 101-102 having cords 103-104 and fans 105 at the rear of the chassis, and interface and cabling 106 at the front of the chassis. The airflow 108 in this example, as induced by the fans 105, is from the rear of the chassis (i.e., the cool aisle) toward the front of the chassis (i.e., the warm aisle). Chassis 100 is mounted in a rack 110 with brackets on the front. That is, the front of chassis 100 is aligned with (and attached to) the front rack posts 111-112 of rack 110. The rear end of chassis 100 is supported by guide rails 121-122, which extend between the front rack posts 111-112 and the rear rack posts 113-114, as illustrated. Note that chassis 100 does not extend the full depth of rack 110. Thus, chassis 100 may be referred to as a ‘shallow’ chassis.

FIG. 2 is an isometric view that illustrates the shallow chassis 100 of FIG. 1 installed in rack 110 above a deeper (full-length) chassis 200. The deeper chassis 200 has its air intake located immediately adjacent to the cool aisle 201, and its air outlet located immediately adjacent to the warm aisle 202. Shallow chassis 100 draws in air from the middle of the rack 110, which is not immediately adjacent to the cool aisle 201. That is, the air intake of shallow chassis 100 is closer to the warm aisle 202 than the air intake of full-length chassis 200. As a result, the air drawn into the shallow chassis 100 is typically warmer than the air in the cool aisle 201, due to recirculation of hot air from the warm aisle 202 (as illustrated by arrow 205) and heating effects of the chassis in the rack 110.

It would therefore be desirable to have an efficient method and structure for reducing the temperature of air drawn into shallow chassis 100.

SUMMARY

Accordingly, the present invention provides a plenum assembly for use with a shallow chassis in a rack-mount system. The rack mount system includes a first set of posts at a first end of the rack, a second set of posts at a second end of the rack, and guide rails that extend between the first and second sets of posts. A shallow chassis mounted on the guide rails extends from the first end of the rack to an intermediate location, between the first and second ends of the rack. The plenum assembly is also mounted on the guide rails, and extends from the second end of the rack to the intermediate location, providing an airway from the second end of the rack to the shallow chassis. In this configuration, air can be drawn directly from the second end of the rack (e.g., the cool aisle), through the airway of the plenum assembly, to the shallow chassis. As a result, recirculation of air from the first end of the rack (e.g., the warm aisle) is eliminated.

In one embodiment, the plenum assembly includes slots for engaging protrusions on the guide rails, and mounting tabs for engaging the second set of posts. A support strut can be included within the plenum assembly to prevent crushing of the airway.

In one variation, the plenum assembly can include telescoping sections, which allow the plenum assembly to be extended to various lengths. In another variation, the plenum assembly has a two piece construction, which can include a tray and a lid. In this variation, tray may be mounted on the guide rails/second set of posts, wherein cables from the shallow chassis are easily routed through the tray. After the cables are routed through the tray, the lid is attached to the tray, thereby forming the airway of the plenum assembly. In a particular embodiment, the lid is slid into slots in the tray.

The present invention will be more fully understood in view of the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a conventional shallow pizza box chassis mounted in a rack.

FIG. 2 is an isometric view illustrating the shallow chassis of FIG. 1 installed in a rack above a full-length chassis.

FIG. 3 is an isometric view of a rack-mountable plenum assembly in accordance with one embodiment of the present invention.

FIG. 4 is an exploded view of the plenum assembly of FIG. 3 in accordance with one embodiment of the present invention.

FIG. 5 is a front isometric view of a shallow chassis installed in a rack, with the plenum assembly of FIG. 3 positioned for insertion into the rack, in accordance with one embodiment of the present invention.

FIG. 6 is a front isometric view of a shallow chassis and the plenum assembly of FIG. 3 installed in a rack in accordance with one embodiment of the present invention.

FIG. 7 is a rear isometric view of a shallow chassis and the plenum assembly of FIG. 3 installed in a rack in accordance with one embodiment of the present invention.

FIG. 8 is an isometric view illustrating the interaction between a shoulder bolt and a mounting slot when the plenum assembly of FIG. 3 is attached to the rack of FIGS. 6 and 7, in accordance with one embodiment of the present invention.

FIG. 9 is a cross sectional view of a plenum assembly having telescoping sections that are capable of sliding along one another, thereby allowing the length of the plenum assembly to be adjusted in accordance with another embodiment of the present invention.

FIG. 10 is an isometric view of a two-part plenum assembly in accordance with an alternate embodiment of the present invention.

FIG. 11 is a cross sectional view of a plenum assembly that includes end portions that extend around a shallow chassis, and also includes a compliant gasket in accordance with alternate embodiments of the present invention.

DETAILED DESCRIPTION

FIG. 3 is an isometric view of a rack-mountable plenum assembly 300 in accordance with one embodiment of the present invention. FIG. 4 is an exploded view of plenum assembly 300 in accordance with one embodiment of the present invention. Plenum assembly 300 includes a first section 301 and a second section 302, that are connected (e.g., by rivets 331-337) to form a hollow air pathway 305. In general, the first and second sections 301-302 form a rectangular box 310, having rectangular openings 310A and 310B at opposing ends. A support strut 303, which is coupled to the first and second sections 301-302 near the middle of the width of the plenum assembly 300, provides support to maintain the shape of the hollow pathway 305 (i.e., prevent crushing of the hollow pathway 305). Plenum assembly 300 includes mounting tabs 311-312 having holes 313-314, respectively. As described in more detail below, screws (or other connector elements) are inserted through holes 313-314 to hold plenum assembly 300 within a rack. As also described in more detail below, holes 313-314 are positioned between screw holes that are used to mount an associated guide rail system in the rack. (See, e.g., FIG. 7.) Plenum assembly 300 also includes mounting slots 321 and 322, which are located to engage with shoulder bolts on a guide rail system in a rack. (See, e.g., FIGS. 6-8 8.) As described in more detail below, plenum assembly 300 is fitted onto the same guide rails as a shallow chassis, thereby bridging the gap that would otherwise exist between the rear of the shallow chassis and the cool air aisle. In this configuration, air from the cool aisle flows through the hollow pathway 305 to the rear of the shallow chassis, advantageously preventing the recirculation of warm air.

As described in more detail below, the cables that extend from the rear of the shallow chassis (e.g., the rear (power) cords of the shallow chassis) are routed through the hollow pathway 305 of plenum assembly 300 in accordance with one embodiment of the present invention. However, it is understood that plenum assembly 300 can alternately include openings that allow top, bottom and/or side cable egress. FIG. 4 illustrates locations 401, 402 and 403, wherein openings can be formed to allow top, bottom and side cable egress, respectively, through plenum assembly 300. In one variation, these openings may be formed by knocking out perforated tabs formed in the plenum assembly 300. In another variation, plugs (or other means for closing the openings) may be included to close these openings if top/bottom/side cable egress is not necessary.

FIG. 5 is an isometric view of a shallow chassis 500 installed in a rack 510 that includes front posts 511-512, rear posts 513-514 and guiderails 521-522, wherein plenum assembly 300 is positioned for insertion into the rack 510. Note that the shallow chassis 500 has already been installed into the rack 510 using the guiderails 521-522, in a manner known to those of ordinary skill in the art. In accordance with one embodiment of the present invention, guide rails 521-522 include corresponding shoulder bolts 601-602, respectively, which extend centrally inward from the guide rails 521-522. Shoulder bolts 601 and 602 are positioned to engage the mounting slots 321 and 322, respectively of plenum assembly 300, thereby supporting the rear of the plenum assembly 300 within the rack 510.

FIG. 6 is an isometric front view that shows plenum assembly 300 mounted to rack 510. FIG. 7 is an isometric rear view that shows plenum assembly 300 mounted to rack 510. In the position illustrated by FIGS. 6 and 7, the mounting slots 321 and 322 have been slid onto the corresponding shoulder bolts 601 and 602 of guide rails 521 and 522. Note that mounting slot 321 and shoulder bolt 601 are shown in dashed lines in FIG. 6, and mounting slot 322 and shoulder bolt 602 are shown in dashed lines in FIG. 7.

The mounting tabs 311 and 312 are attached to center holes on the rear posts 513 and 514 by screws 701 and 702, respectively, thereby holding plenum assembly 300 in place within rack 510. Note that guide rails 521 and 522 also include mounting tabs 521A and 522A, respectively, which are similarly attached to rear posts 513-514 by screws (including screws 701 and 702). Plenum assembly 300 is easily removable from rack 510 by releasing screws 701-702 and sliding the plenum assembly 300 from the rack 510. As illustrated by FIG. 7, the hollow pathway 305 of plenum assembly 300 provides an airway from the cold aisle to the rear of shallow chassis 500, whereby recirculation of hot air from the warm aisle is minimized. As also illustrated by FIG. 7, the power cords 501-502 that are connected to the rear of shallow chassis 500 extend through the hollow pathway 305, and out the back side of the rack 501.

FIG. 8 is a side view illustrating the interaction between the shoulder bolt 601 on guide rail 521 and the mounting slot 321 of plenum assembly 300. The mounting slot 321 includes a large tapered lead-in area 801, which is continuous with a narrower parallel slot 802. The lead-in area 801 facilitates the movement of shoulder bolt 601 into the parallel slot 802 when the plenum assembly 300 is installed in the rack 510.

Although plenum assembly 300 has a fixed length (L), as illustrated in FIG. 3, it is understood that this plenum assembly 300 could be modified to have a telescoping capability to accommodate multiple chassis and rack depths. FIG. 9 is a cross sectional view of a plenum assembly 900 having telescoping sections 901 and 902, which are capable of sliding along one another (as illustrated by the dashed arrows), thereby allowing the length of the plenum assembly 900 to be easily adjusted. Catches or thumbscrews (not shown) can be provided to prevent the telescoping sections 901-902 from coming apart. Although not explicitly illustrated in FIG. 9, it is understood that plenum assembly 900 includes the same general features described above in connection with plenum assembly 300.

Although plenum assembly 300 has been illustrated as having a height to fit a 1 rack unit high chassis, it is understood that plenum assemblies of multiple heights can be designed using the same principles described above.

Although plenum assembly 300 has been described in connection with a configuration wherein the hollow pathway 305 operates as a cold air intake, receiving cold air from the cold aisle, it is understood that plenum assembly 300 can alternately be used as a warm air exhaust. In this embodiment, shallow chassis 500 would be mounted immediately adjacent to the cold aisle, and warm air expelled from shallow chassis would be routed through plenum assembly 300 to the warm aisle.

Plenum assembly 300 requires that power cords (and possibly signal carrying cables) coupled to the rear of shallow chassis 500 to be threaded through the hollow pathway 305 of plenum assembly 300. With this configuration, rear access to shallow chassis 500 may be difficult. In accordance with one variation of the present invention, the plenum assembly 300 is split into two parts to facilitate access to the rear of shallow chassis 500. FIG. 10 is an isometric view of a two-part plenum assembly 1000 in accordance with this variation. Plenum assembly 1000 includes a lower tray 1001 and a lid 1002. Lower tray 1001 includes mounting tabs 1011-1012 and mounting slots 1021-1022, which are similar to the mounting tabs 311-312 and mounting slots 321-322 of plenum assembly 300. The lower tray 1001 is installed in rack 510 in the same manner as plenum assembly 300. Lower tray 1001 is fully open at the top, thereby allowing cables to be easily connected to the rear of shallow chassis 500 after the lower tray 1001 is installed in rack 510. Alternately, lower tray 1001 can be easily installed in rack 510 after the cables have been connected to the rear of shallow chassis 500.

After the cables are connected and lower tray 1001 is installed in rack 510, lid 1002 is attached to lower tray 1001, thereby forming a hollow pathway 1005 between lid 1002 and lower tray 1001. In the illustrated embodiment, the upper edges of lower tray 1001 includes opposing slots 1031-1032, wherein lid 1002 is slid into these slots 1031-1032, as illustrated by the dashed arrows in FIG. 10. Lower tray 1001 includes a connector element 1041 that is aligned with a connector element 1042 on lid 1002 when lid 1002 is slid into lower tray 1001. A fastener 1043 (e.g., screw) may be used to attach connector elements 1041-1042, thereby joining lower tray 1001 and lid 1002, while providing a support that prevents the closing of hollow pathway 1005.

In another embodiment of the present invention, cable management devices, such as cable tie-downs, hooks or channels can be included within the plenum assembly of the present invention to assist with the orderly routing of cables through this plenum assembly (and ensure optimal airflow through these plenum assemblies).

In yet another embodiment, an elastic/compliant gasket can be included on the end of the plenum assembly 300 that abuts shallow chassis 500, wherein the gasket forms a substantially airtight seal between the plenum assembly 300 and the shallow chassis 500, thereby providing efficient airflow through the plenum assembly and minimizing the recirculation of hot air. In another embodiment, the plenum assembly 300 can extend around the shallow chassis 500 on one or more sides, with or without a compliant gasket.

FIG. 11 is a cross sectional view of a plenum assembly 1100 that includes end portions 1101-1102 that extend around the upper and lower surfaces of shallow chassis 500 in the manner suggested above. Note that similar end portions of plenum assembly 1100 can extend around the side surfaces of shallow chassis 500. FIG. 11 also illustrates an optional compliant gasket 1150, which forms a substantially airtight seal between plenum assembly 1100 and shallow chassis 500.

Although the present invention has been described in connection with various embodiments, it is understood that variations of these embodiments would be obvious to one of ordinary skill in the art. For example, although the present invention has been described in connection with a rack mount system having four posts, it is understood that the present invention can be implemented in other types of rack mount systems, including, but not limited to, rack mount systems having two posts (e.g., two front mounting posts or two mid-mount posts). In these embodiments, the manner of attaching the plenum assembly to the rack mount system will be dictated by the specific nature of the rack mount system, and will be apparent to one of ordinary skill in the art in view of the teachings provided herein. For example, the plenum assembly of the present invention may be attached to a rail-based structure of a two post rack mounting system, in a manner similar to that described above. In yet another embodiment, a plenum assembly of the present invention can be engaged with a shallow chassis outside of a rack mount system. For example, the plenum assembly of the present invention can be engaged with a shallow chassis on a tabletop or other non-rack structure. Thus, the present invention is limited only by the following claims. 

We claim:
 1. A plenum assembly comprising: a box having a first opening at a first end and a second opening at a second end, opposite the first end, wherein a hollow pathway extends between the first opening and the second opening; a set of mounting elements located at the first end of the box, wherein the set of mounting elements are configured to engage a first set of posts of a rack; and a pair of mounting slots located at the second end of the box, wherein the pair of mounting slots are configured to engage with a pair of guide rails that extend between the first set of posts of the rack and a second set of posts of the rack.
 2. The plenum assembly of claim 1, wherein the box has a first length between the first end and the second end, and wherein the rack has a second length between the first set of posts and the second set of posts, wherein the first length is less than the second length.
 3. The plenum assembly of claim 1, wherein the set of mounting elements comprise: a first tab that extends from a first surface of the box at the first end of the box; and a second tab that extends from a second surface of the box, opposite the first surface of the box, at the first end of the box.
 4. The plenum assembly of claim 3, wherein the pair of mounting slots comprise: a first mounting slot located in the first surface of the box at the second end of the box; and a second mounting slot located in the second surface of the box at the second end of the box.
 5. The plenum assembly of claim 4, wherein the first mounting slot comprises: a tapered lead-in region continuous with the first end of the box; and a parallel slot region continuous with the tapered lead-in region.
 6. The plenum assembly of claim 1, wherein the second opening of the box has the same dimensions as an end of a chassis mounted on the pair of guide rails.
 7. The plenum assembly of claim 1, wherein the first opening and the second opening are rectangular.
 8. The plenum assembly of claim 1, further comprising a support strut attached to the box within the hollow pathway.
 9. The plenum assembly of claim 1, further comprising one or more openings formed through one or more surfaces of the box.
 10. The plenum assembly of claim 1, wherein the box comprises telescoping sections that slide along one another to vary a length of the box between the first end and the second end.
 11. The plenum assembly of claim 1, wherein the box comprises: a tray; a lid; and means for manually engaging and disengaging the lid and the tray, wherein the lid and the tray form the hollow pathway when the lid is engaged with the tray.
 12. The plenum assembly of claim 1, wherein the box comprises: a tray that forms three continuous surfaces of the box, wherein the tray includes slots on two opposing surfaces; and a lid inserted into the slots of the tray, thereby forming a fourth surface of the box.
 13. The plenum assembly of claim 12, further comprising: a first connector attached to the tray at the first end of the box; and a second connector attached to the lid at the first end of the box; and a fastener that attaches the first connector to the second connector.
 14. A system comprising: a rack; a first set of guide rails extending from a first end of the rack to a second end of the rack; a first chassis mounted on the first set of guide rails, wherein the first chassis extends from the first end of the rack to an intermediate location between the first end of the rack and the second end of the rack; and a plenum assembly mounted on the first set of guide rails, wherein the plenum assembly extends from the second end of the rack to the intermediate location.
 15. The system of claim 14, wherein the plenum assembly includes a hollow pathway that extends from the second end of the rack to the first chassis.
 16. The system of claim 15, wherein the plenum assembly further includes a support strut that extends across the hollow pathway.
 17. The system of claim 15, wherein the plenum assembly comprises: a tray; and a lid that slides into the tray, thereby forming the hollow pathway.
 18. The system of claim 14, further comprising: a second set of guide rails extending from the first end of the rack to the second end of the rack; and a second chassis mounted on the second set of guide rails, wherein the second chassis extends between the first end of the rack and the second end of the rack.
 19. The system of claim 14, wherein the plenum assembly includes a plurality of slots that are engaged with protrusions on the first set of guide rails.
 20. The system of claim 14, wherein the plenum assembly includes telescoping sections that slide over one another, thereby enabling the plenum assembly to be adjusted to extend from the second end of the rack to the intermediate location. 